The H.264 video data compression-coding standard is well known and represents a new generation of video compression-coding that is expected to supersede the widely used MPEG-2 standard for many applications. H.264 achieves higher compression ratios than MPEG-2 but at the cost of greater processing complexity. In some aspects H.264 is similar to MPEG-2; for example, both utilize motion compensation to match current pixel blocks with reference pixel blocks to minimize the differential data that is to be transform-encoded.
One compression encoding option offered under H.264 calls for use of CABAC (context-based adaptive binary arithmetic coding) of syntax elements produced by transform-encoding (including motion vector information and other side data). CABAC potentially offers substantial additional compression efficiency relative to other types of later-stage encoding, but requires considerable processing complexity, particularly in regard to decoding. CABAC decoders for H.264 have been written in software for execution on general purpose processors, but the resulting decoder performance has been less than satisfactory in terms of throughput, especially for decoding a high resolution signal.